More than half of jobs pay less than the “living wage” in some parts of Britain, according to research, with trade union leaders slamming the growing problem of “salary blackspots”.

The Trades Union Congress today released analysis of official figures from the House of Commons Library showing one in five jobs overall in Britain pays less than the living wage.

The findings come as the Low Pay Commission finalises a report recommending how much the national minimum wage should rise from its current £6.50 level – amid union calls for an hourly rate of £7. Birmingham Northfield tops the list of living wage blackspots.

A total of 53.4 per cent of people working in the area earn less than £7.85 per hour. It’s followed by Kingswood near Bristol at 51 per cent, and Dwyfor Meirionnydd in North Wales.

The living wage, calculated according to the basic cost of living, is deemed to be £9.15 an hour in London and £7.85 in the rest of the country.

Frances O’Grady, General Secretary of the TUC, said ensuring that more people earn the living wage was a “vital step” towards tackling the growing problem of “in-work poverty across Britain”. The TUC said the situation was bleaker still for women, with 61 per cent of those working in Birmingham Northfield taking home less than the living wage.

The South-east had some of the highest proportion of workers receiving a living wage. In London’s Poplar and Limehouse, just 7.5 per cent earn below the level.

Shadow Work and Pensions Secretary Rachel Reeves said the growth of low pay under David Cameron “shows the Tory plan has failed millions of working families”.

A spokesman for the Business Department said the Government was committed to improving living standards, particularly for the lowest paid “through preventing exploitation, reducing taxes and increasing employment”.